Deep-water earliest Oligocene glacial maximum (EOGM) in South Atlantic

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doi: 10.1360/04wd0228
Author(s): Liu Zhifei; Tuo Shouting; Zhao Quanhong; Cheng Xinrong; Huang Wei
Author Affiliation(s): Primary:
Tongji University, Laboratory of Marine Geology, Shanghai, China
Volume Title: Chinese Science Bulletin
Source: Chinese Science Bulletin, 49(20), p.2190-2197. Publisher: Science Press, Beijing, China. ISSN: 1001-6538
Note: In English. 31 refs.; illus., incl. sketch map
Summary: The most prominent cooling event of the Earth surface during Cenozoic in the long-term transition from a non-glaciated planet, or "green-house world", to a polar, glaciated planet, or "ice-house world", is the Earliest Oligocene Glacial Maximum (EOGM) above the Eocene/Oligocene boundary at about 33.7 Ma. Planktonic and benthic foraminiferal oxygen and carbon isotopes, carbonate content, and coarse fraction, along with high-resolution color reflectance and magnetic susceptibility records during 35-30 Ma, from deep-water Sites 1262 and 1265, Ocean Drilling Program (ODP) Leg 208 in South Atlantic, reveal the global cooling event occurring in both surface and deep oceans. The results show that the earliest Oligocene δ18O values during 33.5-33.1 Ma represent the magnitude of continental ice sheets on east Antarctica and indicate the large decrease in both surface and deep water temperatures of worldwide oceans. The δ13C records show the large excursion during the period of EOGM event and indicate some types of shift in global carbon reservoir, probably demonstrating the sudden increase in organic carbon burial rates and the changes in the distribution and timing of production. At the same time, lithologic composition, carbonate content, color reflectance, and coarse fraction brought about significant changes close to the Eocene/Oligocene boundary, reflecting the abrupt deepening in the carbonate compensation depth (CCD). Changes in carbonate content were revealed from the color reflectance identify periodicities associated with eccentricity of the Earth's orbit (100 and 400 ka), further indicating orbitally forced global climate variations in the Early Oligocene.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Ancient ice ages; Atlantic Ocean; Bathymetry; Bottom features; C-13/C-12; Carbon; Cenozoic; Climate change; Deep-water environment; Depositional environment; Eocene; Foraminifera; High-resolution methods; Invertebrata; Isotope ratios; Isotopes; Last glacial maximum; Leg 208; Magnetic properties; Magnetic susceptibility; Marine environment; Microfossils; O-18/O-16; ODP Site 1262; ODP Site 1265; Ocean Drilling Program; Ocean floors; Oligocene; Oxygen; Paleoclimatology; Paleogene; Paleomagnetism; Planktonic taxa; Protista; Reflectance; Solutes; South Atlantic; Stable isotopes; Stratigraphic boundary; Tertiary; Walvis Ridge
Coordinates: S300000 S200000 E0050000 W0050000
Record ID: 2005045586
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